chore(*): Add warning message for property rowEditable.

Author: MKirova

projects/igniteui-angular/src/lib/action-strip/grid-actions/grid-editing-actions.component.ts

@@ -104,7 +104,7 @@ export class IgxGridEditingActionsComponent extends IgxGridActionsBaseDirective
         const context = this.strip.context;
         const grid = context.grid;
         if (!grid.rowEditable) {
-            console.warn('The grid must be in row edit mode to perform row adding!');
+            console.warn('The grid must use row edit mode to perform row adding! Please set rowEditable to true.');
             return;
         }
         grid.beginAddRowByIndex(context.rowID, context.index, asChild);

projects/igniteui-angular/src/lib/grids/grid-base.directive.ts

@@ -4066,6 +4066,7 @@ export abstract class IgxGridBaseDirective extends DisplayDensityBase implements
      */
     public beginAddRowByIndex(rowID: any, index: number, asChild?: boolean) {
         if (!this.rowEditable) {
+            console.warn('The grid must use row edit mode to perform row adding! Please set rowEditable to true.');
             return;
         }
         this.endEdit(true);